Self-opening thread rolling head



Feb. 22, 1966 W.4KRUSE- 3,236,081

SELF-OPENING THREAD ROLLING HEAD Original Filed June 14, 1961 United States Patent O 3,236,081 SELF-OPENING THREAD ROLLING HEAD Werner Kruse, Schwarzenbek, near Hamburg, Germany, assignor to Wilhelm Fette Prazisiouswerkzeug-Fabrlk, Schwarzenbek, near Hamburg, Germany Original application June 14, 1961, Ser. No. 117,179, now Patent No. 3,196,650, dated July 27, 1965. Divided and this application Mar. 24, 1965, Ser. No. 442,413 2 Claims. (Cl. 72--78) This invention relates to a self-opening thread rolling head and is a division of patent application Ser. No. 117,179 filed June 14, 1961, now US. Patent No. 3,196,650.

The self-opening head comprises thread-forming rolls freely mounted on eccentric pin elements arranged concentrically around the workpiece and movable with a rocking motion into and out of the working position, and a shank including workpiece stop, these parts being axially displaceable but prevented from relative rotation by a locking device arranged between the body member and the shank, this device being released when the workpiece strikes the stop.

In the known rolling heads of this kind it has been found disadvantageous that a considerable mass must be moved both when releasing and also when closing the locking device so that a strong spring is required and hence, after engagement of the workpiece and rotation of the displaceable part of the housing, there is an undesirably hard impact of this massive part of the housing against a stop limiting the displacement. Also the reengagement of the rolling head, which is effected by rotating the massive part of the housing by hand against the spring force, involves a considerable expenditure of energy.

According to the invention it is therefore proposed that one of the two main parts of the head is further divided and that only a portion of the said part, of comparatively small mass, has to be rotated for opening and closing the thread rolling head.

A self-opening thread rolling head according to the invention comprises two main sections one of which includes freely rotatable threading rolls on eccentric spindles arranged concentrically around the workpiece by which the threading rolls may be moved into and out of the working position and the other consists of a shank portion comprising a hollow shaft and a workpiece stop, in which the section including the threading rolls is axially slidable relatively to the other section and includes two relatively movable parts which, by their relative movement, move the threading rolls towards and away from the working position and are adapted to be held by locking means in that position in which the rolls are in the workpiece engaging position.

The drawing illustrates by way of example a specific embodiment of the invention.

Referring to the drawing the rolling head comprises two main sections, namely a shank section 3 and a body section 4 mounted upon the forward end of the shank section 3. The latter is adapted to be secured to a machine tool in a workpiece-engaging position and either the head or the workpiece is rotated to perform thread rolling. The shank section 3 is hollow and houses a workstop 5 adapted to be engaged by the end of a workpiece being threaded, for the purpose of effecting dis engagement of the thread rolls as explained hereinafter. The workstop 5 is screw threaded for a sleeve 6 at the rear end which is in threaded engagement with a screw threaded bore in the rear end of the shank part 3 and is adapted to be fastened after adjustment by means of a lock nut 7. This adjustment permits the length of thread produced on the workpiece to be adjusted.

3,236,081 Patented Feb. 22, 1966 The body section 4 comprises two relatively rotatable members including a forward member 8 having a splined bore adapted to engage splines formed on the forward part of the shank 3 so that the member 8 can slide axially upon but cannot rotate relatively to the shank 3. The second member of the body section 4 comprises two cylindrical parts 9 and 10 which are adjustably coupled one to the other by means of a spaced series of fastening studs 11. There may be three such studs spaced uniformly around the head and said studs are fixedly screwed into threaded apertures in the part 9 and traverse arcuate slots in the part 10 so that a limited adjustment between these parts is possible. The parts 9 and 10 may be fixed in the adjusted positions by means of nuts 12 on the studs 11 which clamp the part 10 against the part 9. The part 9 may be provided with a circular boss-like portion accommodated within a recess in the rear face of the member 8 and these parts may be held in engagement by means of a ring 15 fixed against an end face of a hub portion of the member 8 by means of fastening screws 16, the outer edge of the ring 15 seating against a stop face of the part 9.

Projecting outwardly from the part 9 is an operating lever 17 by which the parts 9 and 10 may be rotated as a unit relatively to the member 8 for the purpose of closing the thread rolls into the working position ready for engagement with a workpiece to be threaded.

Located in front of the member 8 is a front plate 18 supported from the member 8 by means of spacer blocks 19 which are in threaded engagement with the member 8, the front plate 18 being fastened to the spacer blocks 19 by means of countersunk fastening screws 20. The front plate 18 is centrally apertured at 21 to admit a workpiece to be threaded.

Thread forming rolls 22 are rotatably accommodated upon eccentric spindles 23 by means of needle roller bearings 24. The eccentric members 23 form part of carrier spindles 25 accommodated in apertures in the front plate 18 and in the member 8.

The thread forming rolls 22 are provided with a series of parallel peripheral thread forming grooves and the support spindles 25 are placed slightly obliquely to the center axis of the head at an angle corresponding to the mean helix angle of the thread to be rolled.

The rearmost end of each spindle 25 extends into a recess 26 formed in the body member 8 and carries a projecting arm 27 to which a crank pin 28 is fixed. This crank pin engages a slot 29 in the part 9 so that rotation of the parts 9 and 10 relatively to the member 8 performs rotation of the spindles 26 and thus causes the thread rolls 22 to move into or out of engagement with a workpiece entered through the aperture 21 in the front plate 18.

A spiral spring 30 is provided within a housing formed within the body part 10 and is anchored at one end to said disc part 10 and at the other end to the shank 3. Said spiral spring is designed so as to tend to rotate the body parts 9 and 10 considered as a unit, relatively to the forward member 8 of the body 4 in a direction which tends to move the thread rolls 22 away from the workpiece. The said spring is also adapted to exert an axially directed force upon the body member 4 as a whole tending to force it along the shank part 3 to cause the body member to be locked to the shank 3 by engagement of dogs 31 on the body part 10 with mating dogs of a projecting flange 32 on the shank portion 3. It will be seen that these dogs serve to hold the disc parts 9 and 10 in rotary engagement with the shank 3 and that they are held engaged by the axial force derived from the spring 30. While these conditions apply the threading rolls 22 are locked in the working position and can be brought into operative rolling engagement with a workpiece presented at the aperture 21; relative rotation of the head and the workpiece performs progressive rolling of a thread into the surface of the workpiece which thus moves axially into the head until the workstop 5 is engaged. Thereupon locking engagement is released because the body section 4 as a whole moves in the axial direction upon the shank section 3 until the dogs 31 are disengaged from the dogs on the flange 32 whereupon the spring 30 rotates the parts 9 and 10 of the head relatively to the member 8 and consequently the arms 27 rotate the spindles 25 so that the eccentric portions 23 thereof allow the thread rolls 22 to come out of engagement with the workpiece.

In order to close the rolling head again the parts 9, 10 are moved back against the spring 30 by means of the hand lever 17 until the dogs 31 are re-engaged under the influence of the axial force component of the spring 30.

If the rolling head is used as a rotating head and the workpiece is stationary, the opening action is the same without a special rolling head being required. The rolling head according to the invention is therefore suitable without modification for machining a rotating workpiece or a stationary workpiece.

What I claim is:

1. A self-opening thread rolling mechanism, comprising a hollow supporting shank, a head section splined to said shank for axial sliding movement thereon, eccentric adjusting shafts supported in said head section, threading rolls mounted on said shafts and arranged around the axis of said head, crank arms on said shafts for rotating said adjusting shafts in unison to adjust said threading rollers and move the same radially, a manually operable member associated with said head to rotate about the axis of said shank, yielding spring means for rotating said manually operable member to move said shaft rotating and adjusting means in a direction to move the threading rollers away from the axis of said shank, adjustable stop means in said hollow shank engageable by a workpiece to limit the threading of said workpiece a predetermined distance, and releasable clutch means to lock said manually operable member in a position in which said yielding spring means is placed under tension such that when said workpiece engages said stop, said head section will move in a direction to release said clutch means and permit said spring to rotate said manually operable member and said adjusting shafts.

2. A self-threading rolling head comprising a hollow shank adapted to be supported in a machine tool, in opposition to a workpiece to be threaded, a sectional head having relatively large and small head sections with the large head section splined to and slidably mounted on one end of said hollow shank, a series of shafts journaled in said large section and arranged circumferentially about the axis of said hollow shank, eccentric portions on said shafts, thread rolling rollers rotatably mounted on said eccentric portions, the smaller section of said head being angularly displaceable relative to the larger portion, spring means for yieldingly urging said smaller section in a predetermined direction of rotation and yieldingly urging said larger section in a direction toward said smaller section, clutch means between said smaller section and said shank normally held in engagement by said spring means, crank arm means on said shafts for drivingly connecting said smaller section to said shafts to move the eccentric portions in unison and feed said threading rollers in a direction radially toward and away from the axis of said shank, and an adjustable stop member extending into said shank adapted to be engaged by the workpiece after the same has been threaded a predetermined distance to disengage said clutch means and permit said spring to angularly displace said smaller section and move said threading rollers in a direction away from the axis of said hollow shank while the large'r section supporting said threading rollers remains in fixed relation with said shank.

References Cited by the Examiner UNITED STATES PATENTS 10/1955 Erdelyi et al 72-100 10/1962 Bour 7278 

1. A SELF-OPENING THREAD ROLLING MECHANISM, COMPRISING A HOLLOW SUPPORTING SHANK, A HEAD SECTION SPLINED TO SAID SHANK FOR AXIAL SLIDING MOVEMENT THEREON, ECCENTRIC ADJUSTING SHAFTS SUPPORTED IN SAID HEAD SECTION, THREADING ROLLS MOUNTED ON SAID SHAFTS AND ARRANGED AROUND THE AXIS OF SAID HEAD, CRANK ARMS ON SAID SHAFTS FOR ROTATING SAID ADJUSTING SHAFTS IN UNISION TO ADJUST SAID THREADING ROLLERS AND MOVE THE SAME RADIALLY, A MANUALLY OPERABLE MEMBER ASSOCIATED WITH SAID HEAD TO ROTATE ABOUT THE AXIS OF SAID SHANK, YIELDING SPRING MEANS FOR ROTATING SAID MANUALLY OPERABLE MEMBER TO MOVE SAID SHAFT ROTATING AND ADJUSTING MEANS IN A DIRECTION TO MOVE THE THREADING ROLLERS AWAY FROM THE AXIS OF SAID SHANK, ADJUSTABLE STOP MEANS IN SAID HOLLOW SHANK ENGAGEABLE BY A WORKPIECE TO LIMIT THE THREADING OF SAID WORKPIECE A PREDETERMINED DISTANCE, AND RELEASABLE CLUTCH MEANS TO LOCK SAID MANUALLY OPERABLE MEMBER IN A POSITION IN WHICH SAID YIELDING SPRING MEANS IS PLACED UNDER TENSION SUCH THAT WHEN SAID WORKPIECE ENGAGES SAID STOP, SAID HEAD SECTION WILL MOVE IN A DIRECTION TO RELEASE AND CLUTCH MEANS AND PERMIT SAID SPRING TO ROTATE SAID MANUALLY OPERABLE MEMBER AND SAID ADJUSTING SHAFTS. 